Useful Linux Commands

Following are few useful Linux terminal commands:

1. Shows the list of files with each one in new line with modified time (descending) and read write permissions for each file:

• ls -lrt
• ls -ltr

2. Shows the list of files containing specific word in them. You can use wildcards i.e. * at the beginning, middle or end:

• ls -lrt *all* 
• ls -lrt abc*
• ls -lrt *.xml

3. Lists files with the word after grep. grep searches for particular word: 

• ls -lrt | grep "POS"
• ls -lrt | grep POS
• ls -lrt <folderName> e.g. ls -lrt ABC <-Shows all the files in ABC folder

4. Search word abc in all files' content:

• grep abc *

5. Navigates to the logs folder in current directory's parent.

• cd ../logs

6. Shows the running processes:

• ps -ef
• ps -efww

7. Find particular process in current running processes(Following four lines do the same):

• ps -ef | grep ABC
• ps -ef | grep "ABC"
• ps -efww | grep ABC
• ps -efww | grep "ABC"

8. Commands and description:

• wc -l : Prints the number of lines in a file.
• wc -w : prints the number of words in a file.
• wc -c : Displays the count of bytes in a file.
• wc -m : prints the count of characters from a file.
• wc -L : prints only the length of the longest line in a file.

9. Finds count of files within current folder or directories of current folder:

• find . | wc -l

10. Count number of files containing certain text within current directory:

• grep -l "ABC" * | wc -l

11. Copy file from one linux host (box) to another host:

• scp -P 111 abc.jar username@127.0.2.2:/home/dev

12. Checks for running processes that include abc word and dev word in mentioned format: axo user:20,pid,cmd

• ps axo user:20,pid,cmd | grep dev | grep abc

13. Find 'text' word in files in current directory:

• grep -r "Text" .
• grep "Text" *

14. Find text in file in specified directory:

• grep move test/abc.xml

15. Find text in files in current directory and then within those files, find abc:

• grep -r "Text" . | grep abc

16. Find particular file in Current directory:

• find . -name abc.xml

17. Following commands will find specified text in zipped file and view that file:

• zgrep  "In The File" xyz.zip | less
• zcat xyz.zip | grep "In The File" | less
• zcat xyz.zip | grep "In The File"

18. Find the IP Addresses following URL would resolve to:

• nslookup google.com

19. Show current date and time in current linux box:

• date

20. Show the history of commands executed on current linux box:

• history

21. Goes two directories back:

• cd ../../

22. Given a list of text lines in a file, to display the first 10 lines:

• head foo.txt

23. To display the last 10 lines:

• tail foo.txt
• tail -n3 foo.txt  # the last 3 lines
• head -n4 foo.txt  # the first 4 lines 

24. Show the latest entries in the specified file, in real-time:

• tail -f testfile

25. Following commands moves abc.tar file from current directory to /docs :

• mv abc.tar /docs

26. Following command extracts jar file:

• jar -xvf abc.jar

27. Following command extracts abc.tar:

• tar -xvf abc.tar

28. Following has destination folder to extract abc.tar:

• tar -xvf abc.tar /home/jerry/prog

29. Following command searches ABC word in tarz (zipped folder) files names only, not the content inside files. If u want to grep content, u need to extract the tar ball:

• tar tvf xyz.tarz | grep ABC

30. Command to show the complete current path:

• pwd 

31. Following command shows the processes that are using port 9016

• netstat -tulpna | grep 9016

32. Find text in file located in current directory and sub-directories whose name starts with xyz and ends with xyz

• grep -r "Text" abc*xyz

33. Sets read write execute permissions for all 3 user in all .sh files

• chmod 755 *.sh

34. Create Soft link or shortcut to ./2.5 with name abc:

• ln -s ./2.5 abc

35. Copy directory with files:

• cp -r dir1/ ~/Pictures/

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